An electronic assembly for detecting the presence of police radar signals is generally known and will be referred herein as a radar detector. The radar detector is mounted in a vehicle and provides an audible or visible alert when a police radar signal is detected. The general operation of police radar detectors is described in U.S. Pat. No. 4,313,216; U.S. Pat. No. 4,581,769; U.S. Pat. No. 4,954,828; U.S. Pat. No. 5,049,885; U.S. Pat. No. 5,079,553; and U.S. Pat. No. 5,305,007, all of which are commonly owned by the assignee herein, Cincinnati Microwave, Inc.
Police radar guns broadcast signals in frequency bands which are allocated and regulated by the Federal Communications Commission, as follows: X-band (10.525 GHz.+-.25 MHz); K-band (24.15 GHz.+-.50 MHz); and Ka-band (34.7 GHz.+-.500 MHz). More recently, police radar guns emit pulsed-laser signals in the infrared range.
The radar detector display apparatus described in U.S. Pat. No. 5,305,007 is typical of conventional radar detectors, wherein light emmitting diodes (LED's) are arranged in a linear fashion and illuminated in accord with the detection scheme upon detection of of a valid signal. Similarly, U.S. Pat. No. 4,818,997 describes an analog indicator 108 which indicates the signal strength of a detected signal. Yet another display apparatus is described in U.S. Pat. No. 4,949,088, wherein a siganal indicator 26 is illuminated with different colors to indicate which radar band is active. Still another type of radar detector display apparatus is described in U.S. Pat. No. 5,146,226, wherein the display apparatus has a signal strength LED bargraph 112E, a digital display 112A indicating the number of detected incoming signals, and a LED decimal point 112D which may be illuminated, turned off, or flashed to indicate the radar band of the incoming signal(s).
In some environments, false signals may be detected in a police radar band, such as those commonly transmitted in the X-band by garage door openers or motion detectors, and the radar dectector may be unable to distinguish a true police radar signal from these false signals.
In attempts to provide immunity against false alarms, radar detectors have incorporated signal processing techniques which use software programmable algorithms to discriminate between false and valid police radar signals. Such techniques evaluate the signal characteristics of the detected signal and generate an alert only when the requirements of the detection scheme are satisfied. Such techniques have proven successful in providing immunity against false signals emanating from other police radar detectors, as described in U.S. Pat. No. 5,305,007. However, such solutions may be costly to implement.
Conventional radar detector displays indicate the radar band and signal strength of an detected signal. However, such information is not useful if the detected signal is not a valid police radar signal, but instead, a signal from another radio source broadcasting within the same radar band. As the number of radio sources broadcasting signals within police radar bands continues to grow due to usage of motion detectors, remote controls for garage doors and the like, the need for a low cost solution which permits identification and discrimination of such false signals is evident. Accordingly, it would be desirable to have an apparatus which could provide information to assist the user in distinguishing valid police radar signals from false signals occurring within the same radar band.